Tubular goods such as drill pipe and casing string sections are widely used in oil and gas exploration or production activities and like applications. Such tubular goods must be inspected for latent structural defects to prevent failure under working conditions. Radiation has been used for this purpose, with a detector situated either to sense radiation passing through a wall or to sense backscatter radiation from an irradiated surface.
Conventional backscatter detection inspection systems have incorporated a camera containing a radiation source. A camera in the context of this field of technology is an active emitter of energy, with the radiation detector considered as a separate, passive energy receptor. Radiation emission is directed toward the object to be inspected through an orifice in the camera regulated by an electrically activated, manually controlled shutter mechanism. These existing designs have recognized the risk of accidental exposure to radiation for operating personnel or others adjacent the device. This may occur if the shutter mechanism is left open, either by operator error or upon the loss of electrical power to the camera which enables the operator to manipulate the shutter mechanism. The risk of accidental exposure is drastically increased if a tubular member is not in position in front of the camera, such as may intermittently be the case during inspection operations. Under these conditions, radiation would be allowed to indiscriminately diffuse away from the camera without warning.
To counteract this, conventional designs have included a large block of radiation opaque material positioned across from the camera as a backup to absorb radiation which normally encounters a tubular member. However, this feature suffers from several undesirable inefficiencies and limitations. To the extent that radiation is still allowed to pass from the camera to the block with the shutter left open, a risk of accidental exposure remains. Secondly, the apparatus may become damaged to the point that the camera is misaligned and the block is rendered useless. Finally, backscatter detection inspection systems are frequently mounted on a flange which is rotated at high speed around an opening through which the tubular member is passed, in order to provide complete exposure to the radiation. This procedure is made considerably more difficult and less energy efficient by the presence of the massive block which must also be rapidly rotated with the camera during inspections.
Therefore, it is a feature of the invention to provide an improved backscatter detection inspection apparatus for tubular goods.
It is another feature of the invention to provide an improved radiation camera having a shutter mechanism which automatically prevents the emission of radiation upon the loss of electrical power to the camera.
These and other objects advantages and features of the invention will be apparent to those skilled in the art, from consideration of the specification, including the attached drawings and appended claims.